Effect of repeated testing on contrast sensitivity

The effect of repeated testing on contrast sensitivity was examined across days and between eyes with the Nicolet CS-2000 Vision Tester. Monocular contrast sensitivity functions (CSF's) were measured with the standard technique for training days 1 to 5 on a group of 20 subjects. The group was then divided into four groups of five subjects each. A single post-training CSF was obtained for each group 1, 3, 5, or 7 days after the cessation of training. Results show that there is no measurable effect of practice on contrast sensitivity over a 5-day training period, nor is there any decrease in performance in the absence of training. CSF's were also obtained on both eyes of a separate group of subjects. We found no transfer of learning either between eyes within a single session or across multiple training sessions. We conclude that although the absence of a significant practice effect has important clinical advantages, the variability of the technique is high, allowing only robust experimental effects to be detected.